Conventional blood bags carry a blood collection needle which is attached to a hub, to preserve sterility of the needle. A removable sheath or needle cover is positioned about the needle, and removably attached to the hub.
Generally, the sheath is made out of rubber or plastic, and may be removed by twisting. In one prior art embodiment (Pagones U.S. Pat. No. 3,523,530) the sheath is formed integrally with the hub, being connected thereto by a thin, frangible ring of plastic through which the needle protrudes from the hub into the sheath. Accordingly, for removal of the sheath, it is merely twisted to break the frangible plastic ring.
One serious drawback to this sort of arrangement is that, upon twisting of the sheath, it is possible for the pointed needle end to dig into the inner wall of the sheath, scouring out a small piece of plastic which may remain within the hollow-pointed end of the needle, or on a sharp edge. This is obviously most undesirable, since the plastic piece may be implanted into the arm of a blood donor if it is not noticed. Even if it is noticed, it will have to be removed by the user, which tends to threaten the sterility of the needle.
As a further disadvantage relating to the needles of blood bags and the like, in many designs, the blood preservative such as ACD or CPD can pass upwardly through the tip of the needle to wet the outside thereof. This can result in an unpleasant burning sensation in the skin during veinopuncture.
In accordance with this invention, the above disadvantages are eliminated to provide a more reliable puncturing needle, free of plastic shards or of danger of blunting the needle through scraping contact with the needle cover during removal, where the needle is sealed so that its exterior is not wetted by the contents of the blood bag.
It is also contemplated that the invention of this application can be used for other needle covers, such as for administration sets and the like which are used for purposes other than blood collection.